with all the trouble you would go through cutting frames, rewelding them, making sure there lined up properly,and running the risk of messing them up, u can take the 250r/400ex frame you where going to cut in half, and fab up some new motor mounts, plastic mounts (unless you want it to look like a 250r?) and get some 250r parts and put it together like that ofcourse this would prolly cost more but me myself i think this would be easier and safer